ggtern: Ternary Diagrams Using ggplot2

Abstract

This paper presents the ggtern package for R, which has been developed for the rendering of ternary diagrams. Based on the well-established ggplot2 package (Wickham 2009), the present package adopts the familiar and convenient programming syntax of its parent. We demonstrate that ggplot2 can be used as the basis for producing specialized plotting packages and, in the present case, a package has been developed specifically for the production of high quality ternary diagrams. In order to produce ggtern, it was necessary to overcome a number of design issues, such as finding a means to modify existing geometries designed for a 2D Cartesian coordinate system and permitting them to function in an environment that requires an additional spatial aesthetic mapping. In the present paper, we provide examples of this package in its most basic form followed by a demonstration of its ease of use, particularly if one is familiar with, and has a predilection towards using ggplot2 on a regular basis.